There are known units in the prior art for picking up spare wheels designed for their use on vehicles, and more specifically units designed in picking up or releasing a spare wheel which is disposed beneath the chassis (or on the underside) of the vehicle.
These units comprise a main shaft connected to the wheel and supporting it, a mechanism with a power shaft, which may be of different types, which allow a cable to be wound or released when the user acts on the power shaft with a tool, the cable being connected at one end to the main shaft and at the other to the mechanism, said mechanism withstanding the tension transmitted by the cable due to the weight of the wheel, and the mechanism being designed so that the power shaft is locked, and its movement therefore being irreversible, and it only being able to rotate again in any direction when the user acts on it with the tool. The units also comprise a safety device that is activated when the tool stops acting on the power shaft.
U.S. Pat. No. 6,267,546 discloses a unit of this type. Said unit comprises a main shaft with a support for the wheel, a mechanism connected to the main shaft acted on by the user with a tool, with a cable for raising or lowering said main shaft, and therefore the wheel, between an upper position and another lower position, and a safety device. Said safety device comprises a sliding bolt adapted to support the main shaft, and therefore the wheel, and an actuator adapted to selectively move the bolt between a locking position in which the safety device supports the main shaft, and an unlocking position in which the movement of said shaft is released. The safety device is always in an active position, and the bolt is in the locking position, and therefore supporting the main shaft, when the tool is not acting on the mechanism.